Cleaning Clean Rooms

Here, a prototype balloon for studying the atmosphere of Venus is constructed in a clean room at JPL. Spacecraft are constructed in clean rooms in order to prevent dust particles and contaminants from damaging sensitive equipment or interfering with experiments.Credit: NASA/JPL-Caltech

NASA clean rooms, where scientists and engineers assemble spacecraft, have joined hot springs, ice caves, and deep mines as unlikely places where scientists have discovered ultra-hardy organisms collectively known as ‘extremophiles’. Some species of bacteria uncovered in a recent NASA study have never been detected anywhere else.

According to Dr. Kasthuri Venkateswaran, who led the study conducted at NASA’s Jet Propulsion Laboratory in Pasadena, California, “These findings will advance the search for life on Mars and other worlds both by sparking improved cleaning and sterilization methods and by preventing false-positive results in future experiments to detect extraterrestrial life.”

NASA builds its spacecraft in rooms designed to minimize contamination by airborne particles because dust and its microbial passengers can foul instruments and invalidate experiments. If scientists someday find microbes on Mars, they will want to be sure they aren’t just hitchhikers from Earth.

Clean rooms used in the space program already undergo extensive cleaning and air filtering procedures, and the detection technology employed in this study will help NASA to develop and monitor improvements. Still, it is extremely difficult to eliminate all dust particles and microbes without damaging the electronic instruments the process is intended to protect.

Identifying and archiving clean-room microbes serves as an effective backup to the cleaning and sterilization efforts. Armed with a list of microbes that could possibly stow away on its spacecraft, NASA can disregard them if they turn up in future Martian samples.

In the Payload Hazardous Servicing Facility at NASA’s Kennedy Space Center in Florida, a clean room technician takes a measurement on the Phoenix spacecraft. The Phoenix lander is currently en route to Mars where it will search for signs of water and life below the planet’s surface.Credit: NASA/Kim Shiflet

As reported in FEMS Microbiology Ecology, a journal of the Federation of European Microbiological Societies, Venkateswaran’s team used a technology known as ribosomal RNA gene-sequence analysis to detect bacteria in clean rooms at Kennedy Space Center, Johnson Space Center, and the Jet Propulsion Laboratory. This was the first time that this technology was applied to NASA clean rooms.

They found that both the total number of bacteria and the diversity of bacterial species were much higher than previously detected. This has implications not only for NASA and other space agencies, but also for hospital operating rooms and industries such as semiconductor manufacturing, where cleanliness and sterility are critical.

Clean rooms are considered extreme environments for microbes because water and nutrients are in extremely short supply. Nevertheless, some bacteria are able to survive on what little moisture the low-humidity air provides and on trace elements in the wall paint, residue of cleaning solvents, and in the spacecraft materials, themselves.

The robotic arm of NASA’s Phoenix lander, which will dig below the martian surface, was sterilized before the lander was launched in order to prevent a false detection of biological signatures on Mars.Credit: NASA/JPL/UA/Lockheed Martin